就是这一小块,难了半天,最后看题解才发现递推公式搞错了。。。

we[i][j] = Math.max(we[i+1][j],we[i][j-1]);

import java.util.*;
public class Main{
    public static void main(String[] args){
        Scanner input = new Scanner(System.in);
        String s = input.next();
        char[] list = s.toCharArray();
        int j=0;
        int li,rj;
        int max =0;
        int re=1;
        int[][] we = new int[list.length][list.length];
        for(int i =0;i<list.length;i++){
            we[i][i] = 1;

        }
        
        for(int l =2;l<=list.length;l++){
            for(int i = 0 ;i<list.length;i++){
                max =0;
                j = l+i -1;
                if(j >=list.length){
                    break;
                }
                if(list[i] != list[j]){
                    //就是这一小块,难了半天,最后看题解才发现递推公式搞错了。。。
                    we[i][j] = Math.max(we[i+1][j],we[i][j-1]);
                }else{
                    if(j-i<2){
                        we[i][j] = 2;
                    }
                    else{
                        we[i][j] = we[i+1][j-1] + 2;
                        
                    }
                }
                if(we[i][j] > re){
                    re = we[i][j];
                }
            }
        }
        System.out.print(re);
    }
}